With the advent of frequency dependent products such as electronic watches, color television, mobile communication equipment, etc., there has been a substantial increase in the use of crystals as frequency controlling elements. The important characteristics of a crystal are its impedance and its resonant and/or anti resonant frequency at a given power dissipation. Meters used to determine crystal frequency and impedance are generally referred to as crystal impedance meters. The resistance substitution technique is employed, that is, a crystal and a resistor alternately are connected into an oscillator circuit which is tuned to oscillate at the resonance frequency of the crystal. Present crystal impedance meters are not entirely satisfactory as the crystal impedance is measured at an arbitrarily set drive voltage and furthermore, calculations are required to determine the crystal power dissipation.
A crystal impedance meter made in accordance with this invention operates on the resistance substitution technique making it compatable with present measuring techniques. The crystal frequency and impedance are determined under conditions corresponding to the crystal power levels in actual use, with the power dissipation of the crystal measured directly.